Mix masa and salt in a medium sized bowl. In microwave, boil water and shortening into a separate pan or bowl. Pour this mixture into the bowl of masa and mix with a fork. Will be crumbly.

When cool enough to touch mix the dough with your hands. The dough will probably be a little dry. Add hot water one teaspoon at a time until the dough stays together and doesnt crumble apart.

Knead the dough for one or two minutes. Play with the consistency by adding more water if needed. What you want is a dough that is moist enough to stay together but not too sticky.

Preheat cast iron pan or comal over med-high heat. No need to lubricate.

Pinch off some dough and roll into smooth round balls (golf ball size) with your hands. Covering dough youre not working with, with either plastic wrap. Flatten the ball a bit in the palm of your hand.

Pressing: If you are using a tortilla press, cut a Ziploc type bag down both sides. Open like a book. Lay one side on tortilla press then place the slightly flattened dough on top. Fold other side of ziplock over the dough and close the lid to flatten the dough.

Carefully peel the top piece of plastic from the tortilla. Lift the plastic from the press and place it in your hand, dough side down. Gently peel the bottom piece of plastic from the tortilla. If dough sticks excessively, it probably means dough is too wet. Try adding a sprinkle of corn flour and kneading the dough a bit more.

Cooking: Place your tortilla in the preheated pan and cook for 45 seconds to a minute on each side. Place cooked tortillas in foil and cover with a clean kitchen towel to keep warm. Store in a Ziploc bag in the refrigerator for several days.